Core D: Biomarkers and Biobanking Core?Abstract The Health and Aging in Africa: Longitudinal Studies of an INDEPTH Community (HAALSI) Program Biomarkers and Biobanking Core (Core D) will be critical to achieving the goals of all five projects and for enabling both internal and external collaboration that can extend over a long period of time and across a broad research network. Biobanking research has become a cornerstone of modern population-based study approaches to ensure that maximum benefit is derived from existing resources and collected data and samples and to enhance knowledge generation and discovery potential.1, 2 Biomarker measurement and assessment is an objective measure of parameters that provide information on the state of health of an individual at the time of collection as well as on their inherent genetic risk or predisposition for specific traits or diseases. Longitudinal biomarker measurements planned for the HAALSI study will allow the tracking of changes in various biomarkers with increasing age and with a changing environment, for example, in the context of high rates of HIV infection, famine, lifestyle changes, and greater access to health care. Through collaboration with the African Wits-INDEPTH Partnership for the Genomic Study of Body Composition and Cardiometabolic Disease Risk (AWI-Gen) Collaborative Center,3 which is part of the Human Heredity & Health in Africa (H3Africa) Consortium,4 we will have access to genome-wide data on genetic variation that can be analyzed in the context of the phenotypic data we will be collecting in the HAALSI Program. The depth of information will make it possible to assess potential population stratification and to build in corrective measures to circumvent population sub-structure as a confounding variable in comparative genomic studies. The expertise of the Core D leaders and its collaborating investigators will ensure appropriate and extensive blood and urine biomarker analysis and genomic investigations (including telomere length and epigenetic DNA methylation analysis), as well as data analysis and interpretation. The paucity of health biomarker data from African populations5-8 makes the proposed HAALSI Biobank and its biomarker testing capacity an extremely valuable resource, not only for the study of the substantive HAALSI cohort of 5,059 participants, but also for future research investigations. Its value, however, can only be secured through good governance practices for biobanking and biomarker measurement and data storage and management.